Rain on Freshly Placed Sealer

By Chris Sullivan - ChemSystems, Inc.

Rain on concrete within an hour after sealing causes blisters and water marks on the sealed surface.

Question:

My new (35 days old) concrete deck is stamped, and my wife and I acid stained it this weekend. I washed it with high pressure and light brooming, per the stain manufacturer's recommendations, and rolled on a solvent-based acrylic sealer. I sealed it less than 12 hours after washing, and I know now that was not a good idea. I used a ¾-inch-nap roller to apply the sealer, per my concrete installer's recommendation. I aggressively worked it in the grooves to ensure everything was sealed.

An hour after I finished applying the sealer, it rained. So now I have a bunch of blisters and rain spots, and plenty of roller marks to address. I used a 5-gallon pail of sealer for the job, so I don't think I applied too much, and the manufacturer said that I didn't overdo it by using that amount on 1,600 to 1,700 feet of textured surface.

Should I spray or roll xylene all over the deck and see what happens? I plan to spray another thin layer of sealer when done, so it's OK if it strips some of the existing sealer. I just ordered a sprayer, which was also recommended by the sealer manufacturer. I want to add some SharkGrip to the sealer as well for slip resistance, and I have read that if the proper amounts are mixed, and mixed well, it will spray fine through the sprayer.

Answer:

The good news is that the fix is actually pretty straightforward. As long as you are OK with the stain color and appearance, the sealer is your only issue. This can be fixed with the next coat of sealer or using a solvent bath. You are good on your application rate, so no issues there. Your best bet is to spray apply the next coat of sealer at the same rate, and then have someone else back roll right next to you. The second coat of sealer will melt the first coat, then the back rolling while the sealer is wet will help lay it down and get rid of the bubbles and blisters. Only one or two roll passes are necessary. Maintain a wet edge, and don't overwork it. This should also get rid of the water marks from the rain.

Be sure to apply the sealer when it will remain rain-free for 24 hours after sealing. Using the grit additive in your second coat is not an issue, as long as you follow the manufacturer's recommendations and mix well.